Radio-Frequency Identification (RFID) Tags for Liquid Monitoring

ABSTRACT

Example embodiments relate to radio-frequency identification (RFID) tags for liquid monitoring. An example RFID tag includes an antenna configured to communicate with an RFID reader. The antenna includes a radiating plane. The antenna also includes a ground plane. The RFID tag is attachable to a container. A reactance associated with the antenna is modifiable based on a temperature and a volume of a liquid within the container and adjacent to the ground plane. The RFID tag also includes an integrated circuit that includes a memory. The integrated circuit is configured to modulate the antenna in response to an RFID signal from the RFID reader based on the reactance associated with the antenna.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application claiming priorityto U.S. patent application Ser. No. 17/522,479, filed with the U.S.Patent and Trademark Office on Nov. 9, 2021, which claims priority toProvisional Patent Application No. 63/113,474, filed with the U.S.Patent and Trademark Office on Nov. 13, 2020. The contents of each ofwhich are hereby incorporated by reference.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Many industries today rely on radio-frequency identification (RFID)technology to identify, track, and authenticate items. For example, RFIDsystems may be utilized to determine the current location of articles ofinterest, inventory control and tracking, asset tracking and recovery,and the like. RFID technology can achieve substantial cost-savings andother operational improvements relative to alternative means oftracking, such as human-readable labels or machine-read barcodes.

SUMMARY

Disclosed herein are RFID tags, systems, and methods that can be used tolabel/track various items (e.g., liquid containers). The RFID tags,systems, and methods described herein may simultaneously providemonitoring of the temperature of the item being labeled and a liquidlevel or liquid volume associated with the item (e.g., how much liquidis present within a container). The temperature may be determined by theRFID tag using a temperature sensor of the RFID tag. Further, the liquidlevel may be determined by the RFID tag based on a change in thereactance of an antenna of the RFID tag.

In one aspect, a radio-frequency identification (RFID) tag is provided.The RFID tag includes an antenna configured to communicate with an RFIDreader. The antenna includes a radiating plane. The antenna alsoincludes a ground plane. The RFID tag is attachable to a container. Areactance associated with the antenna is modifiable based on a volume ofa liquid within the container and proximate to the ground plane. TheRFID tag also includes an integrated circuit that includes a memory anda temperature sensor configured to provide information indicative of atemperature of the liquid within the container. The integrated circuitis configured to: in response to an RFID signal from the RFID reader,modulate the antenna based on the reactance associated with the antennaand a temperature reading of the temperature sensor to provideinformation indicative of the volume of the liquid within the containerand the temperature of the liquid within the container.

In another aspect, a system is provided. The system includes a containerconfigured to be filled with a liquid. The system also includes aradio-frequency identification (RFID) tag attached to the container. TheRFID tag includes an antenna configured to communicate with an RFIDreader. The antenna includes a radiating plane. The antenna alsoincludes a ground plane. A reactance associated with the antenna ismodifiable based on a volume of the liquid within the container andproximate to the ground plane. The RFID tag also includes an integratedcircuit that includes a memory and a temperature sensor. The temperaturesensor is configured to provide information indicative of a temperatureof the liquid within the container. The integrated circuit is configuredto: in response to an RFID signal from the RFID reader, modulate theantenna based on the reactance associated with the antenna and atemperature reading of the temperature sensor to provide informationindicative the volume of the liquid within the container and thetemperature of the liquid within the container.

In an additional aspect, a method is provided. The method includesreceiving, at a radio-frequency identification (RFID) tag, an RFIDsignal transmitted by an RFID reader. The RFID tag includes an antenna.The antenna includes a radiating plane. The antenna also includes aground plane. The RFID tag is attached to a container. A reactanceassociated with the antenna is modifiable based on a volume of a liquidwithin the container and proximate to the ground plane. The RFID tagalso includes an integrated circuit that includes a memory and atemperature sensor configured to provide information indicative of atemperature of the liquid within the container. The method also includesmodulating, by the integrated circuit in response to the RFID signal,the antenna based on the reactance associated with the antenna and atemperature reading of the temperature sensor to provide informationindicative of the volume of the liquid within the container.

These as well as other aspects, advantages, and alternatives will becomeapparent to those of ordinary skill in the art by reading the followingdetailed description, with reference, where appropriate, to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration of a system, according to exampleembodiments.

FIG. 1B is an illustration of a system, according to exampleembodiments.

FIG. 1C is an illustration of an illustration of a shift in a frequencyresponse associated with an antenna, according to example embodiments.

FIG. 1D is an illustration of a frequency response plot for an RFID tag,according to example embodiments.

FIG. 1E is an illustration of a frequency response plot for an RFID tag,according to example embodiments.

FIG. 1F is an illustration of a sensor code lookup table for an RFIDtag, according to example embodiments.

FIG. 2A is an illustration of an RFID tag, according to exampleembodiments.

FIG. 2B is an illustration of surface current for an RFID tag, accordingto example embodiments.

FIG. 2C is an illustration of surface current for an RFID tag, accordingto example embodiments.

FIG. 2D is an illustration of directivity of an antenna of an RFID tag,according to example embodiments.

FIG. 2E is an illustration of directivity of an antenna of an RFID tag,according to example embodiments.

FIG. 3 is an illustration of a system, according to example embodiments.

FIG. 4 is a flowchart illustration of a method, according to exampleembodiments.

DETAILED DESCRIPTION

Example methods and systems are contemplated herein. Any exampleembodiment or feature described herein is not necessarily to beconstrued as preferred or advantageous over other embodiments orfeatures. The example embodiments described herein are not meant to belimiting. It will be readily understood that certain aspects of thedisclosed systems and methods can be arranged and combined in a widevariety of different configurations, all of which are contemplatedherein.

Furthermore, the particular arrangements shown in the figures should notbe viewed as limiting. It should be understood that other embodimentsmight include more or less of each element shown in a given figure.Further, some of the illustrated elements may be combined or omitted.Yet further, an example embodiment may include elements that are notillustrated in the figures.

Additionally, the principles described herein (e.g., related to antennadesign and/or operation) may be applied to different embodiments. Forexample, embodiments described herein may encompass different types ofliquid containers (e.g., containers made of different materials),different shapes of liquid containers, different sizes of liquidcontainers, different types of liquid within those containers, differentvolumes of liquid within those containers, etc.

I. Overview

An RFID tag is provided for measuring a temperature and/or an amount ofliquid in a container to which the RFID tag is attached. In someexamples, the RFID tag may be specifically configured for consumerapplications (e.g., household cleaning products, beverage containers,gasoline tanks, etc.) or sensitive medical transportation applications(e.g., when transporting and/or storing biological samples, medication,or vaccines), where maintaining a desired liquid temperature and knowingthe level and/or volume of liquid in the container is important. TheRFID tag may be configured to provide such information throughout thelife cycle of a tagged container (e.g., a 2.25 mL medical vial utilizedin pharmaceutical/biotech applications). In an example embodiment, theRFID tag may provide information indicative of an initial undilutedvaccine liquid level amount (e.g., 0.45 mL), a diluted vaccine liquidlevel amount (e.g., 2.0 mL), and liquid levels between 2.0 mL and 0.0 mL(e.g., in 0.5 mL intervals) as the undiluted vaccine is diluted and asthe diluted vaccine is distributed from the vial.

The RFID tag may include a monopole or quarter-wave antenna (e.g.,inverted f-type) design. The RFID tag may also include an integratedcircuit configured to detect and report a change in a reactance value ofthe associated antenna. For example, the RFID tag may include the AXZONMAGNUS-S3 M3D integrated circuit (or similar integrated circuit) or anyintegrated circuit that is able to detect and report a change in theantenna's reactance. The change in liquid level may correspond to achange in the reactance associated with the antenna, which may cause achange in a frequency response associated with the antenna. As such, achange in frequency response can be correlated to a specific liquidlevel in the container. In some embodiments, the liquid levelinformation may be recorded in an on-board memory and can be reported toan RFID reader as a sensor code value (e.g., between 5 and 470) and/or achange in the capacitance/reactance value detected by the integratedcircuit in response to interrogation by the RFID reader. Further, thechange of frequency response may be stored and/or communicated as apercentage change (e.g., a percentage change ranging 3-10%) or as a rawchange in Hz (e.g., a raw change ranging between 20 MHz and 30 MHz, suchas 25 MHz). Additionally or alternatively, in some embodiments, thechange of frequency response may be stored and/or communicated relativeto the Federal Communications Commission (FCC) waveband (902-928 MHz) oranother waveband (e.g., the European Telecommunications StandardsInstitute (ETSI) waveband).

As described above, in some applications, it can be desirable to monitortemperature and liquid level within a container over time. For example,in some medical applications (e.g., when delivering medication,vaccines, or biological samples) a container (e.g., a vial or a syringe)may experience a range of temperatures and liquid levels throughout itslifetime. A medication or a vaccine, for instance, may be transported,in bulk, at a first temperature (e.g., a very low temperature between−100° C. and −60° C.) with a first dilution level (e.g., undiluted), maybe stored at a second temperature (e.g., a low temperature between −20°C. and 0° C.) with a second dilution level (e.g., undiluted), and thenmay be administered to a patient at a third temperature (e.g., a roomtemperature between 20° C. and 30° C.) and a third dilution level (e.g.,diluted to a specific molarity based on a dosage amount and/or a methodof administration to the patient).

Likewise, beverages (e.g., alcoholic beverages) may be provided to acustomer (e.g., at a bar or restaurant) in a container (e.g., a bottle,a pint glass, a plastic cup, or a coffee cup) and it may be desirable tomonitor the temperature and liquid level of that container over time.For example, if a customer's beverage runs low, a bartender or servermay wish to offer the customer a refill or, if a customer's beveragechanges temperature undesirably, a bartender or server may wish to offerto modify the temperature of the customer's beverage (e.g., by addingone or more ice cubes or by adding additional hot liquid, such asadditional coffee). Additionally or alternatively, it may be desirableto control a volume of a given beverage provided to a customer tomonitor a stock (i.e., reserve inventory) of the given beverage timeand/or to ensure sufficient stock over a period of time. This mayprovide a warning to a bartender that a stock should be replenished inadvance of the entire stock being depleted. Still further, it may bedesirable to monitor the temperature of a liquid in a container toensure the temperature comports with certain standards (e.g., to ensurecoffee is within an appropriate range of temperatures to be consumed orto ensure that drugs are not being exposed to unsafe temperatures whichwould result in a loss of potency). Yet further, it may be beneficial tomonitor liquid level and temperature of beverages that are distributeddirectly to customers via a grocery store to ensure that, for example,the beverages remain at an appropriate storage temperature (e.g., inapplications involving wine or beer) and does not leak (e.g., to ensurethe integrity of glass bottles) prior to being sold to the customer. Inaddition to monitoring a liquid level and/or temperature, embodimentsdescribed herein could be used to monitor a time elapsed (e.g., relativeto an expiration date of a liquid) relative to when the container wasopened (e.g., first exposed to air). The integrated circuit of RFID tagsdescribed herein may store, using a timer option of the integratedcircuit, a time elapsed and may compare the time to an expiration date(e.g., stored within a memory of the integrated circuit). The RFID tagmay also communicate the expiration date, time elapsed since opening ofcontainer, and/or the expiration status (e.g., expired, not yet expired,time remaining to expiration, etc.) to an RFID reader using the antenna.

Additionally or alternatively, some examples could include monitoringthe production of mixed liquid products, such as carbonated beverages.For example, a container may be partially filled with a chilled flavoredsyrup, followed by filling a substantial remaining volume of thecontainer with carbonated water. Embodiments herein may be utilized toconfirm proper solution preparation. It will be understood that othertypes of liquid manufacturing processes may be monitored with an RFIDtag configured to measure temperature and liquid volume.

In yet another application, it may be desirable to monitor a liquidlevel and temperature of fuel (e.g., gasoline) within a fuel tank.Monitoring the temperature may ensure that a combustible liquid is notoverheated to a dangerous level. Further, monitoring the liquid levelmay ensure that a corresponding machine (e.g., vehicle) does not run outof fuel at an inopportune time.

In each of the applications described above (and many others notlisted), it may be desirable to monitor the liquid level and/or thetemperature of a liquid within a container. However, due to the sizeand/or form factor of the corresponding container, the location in whichthe container is stored, the way in which the container is transported,the average temperature at which the temperature is stored, requirementsfor hermetic sealing, or other factors, it may be difficult orimpractical to open the container or otherwise access the liquid so asto measure the liquid level or temperature. Further, to conserve time,it may be desirable to have an individual tag on each of a number ofcontainers (e.g., within a set of containers) that can communicate theliquid level and temperature of the container efficiently back to acomputing device or technician.

Hence, described herein are RFID tags capable of communicating both thetemperature and the liquid level of a liquid within a container. Forexample, the RFID tags may be adhered to a container (e.g., a glasscontainer or a plastic container) and may measure the temperature andthe liquid level of the liquid within that container. The measuredliquid level may also be indicative of a dilution level of the liquid ifthe liquid is a solution or mixture (e.g., based on a known quantity ofunderlying solute in addition to the volume of the liquid). Such adilution level may indicate a dosage level of a medicine or an alcoholby volume (ABV) level of a beverage, for example. The liquid level andtemperature may be communicated to an RFID reader (e.g., with anassociated timestamp) in response to an RFID signal received from theRFID reader, for example.

In order to measure the temperature of a liquid in the underlyingcontainer, the RFID tag may include a temperature sensor (e.g., atemperature sensor that is integrated within the integrated circuit).Further, in order to communicate with the RFID reader (or otherdevices), the RFID tag may include an antenna (e.g., with a ground planeand a radiating plane). This antenna may generate electromagnetic wavesto communicate a message (e.g., a code) to the RFID reader (e.g., inresponse to an RFID signal from the RFID reader). In addition, though,the antenna may be usable (e.g., by an integrated circuit of the RFIDchip, such as the AXZON M3D) to monitor a liquid level of the liquid inthe underlying container. As the liquid level in the container rises orfalls, a reactance value associated with the antenna may also change(e.g., because the dielectric constant associated with theliquid/container combination is changing due to a change in theproportion of liquid vs. the proportion of air within the container).This change in reactance is reflected in a frequency response associatedwith the antenna. In other words, the intensity at which the antenna canbe excited at different frequencies will change based on the change inreactance (e.g., the resonant frequency associated the antenna willchange). Hence, by measuring the change in frequency response associatedwith the antenna, an underlying change in reactance and, therefore, anunderlying change in liquid level can be deduced (e.g., based on one ormore of the plots in FIGS. 1D-1F). In this way, an integrated circuit ofthe RFID chip can measure a change in the liquid level using the RFIDantenna, itself, rather than requiring an auxiliary sensor in order tomeasure liquid level.

When an RFID signal is received by the RFID tag, the RFID tag maycommunicate a response to the RFID tag. For example, the RFID tag maytransmit an RF wave to communicate a message to the RFID reader.Additionally or alternatively, one or more components of the RFID tagmay be modulated (e.g., a signal transmitted by the antenna ismodulated) in such a way that is measurable by the RFID reader toreceive a signal. For example, the RFID reader may be inductivelycoupled to the RFID tag, and an impedance of the RFID tag may bemodulated so as to communicate a message to the RFID reader. In responseto receiving the RFID signal from the RFID reader, the RFID tag maycommunicate a response that includes an identification code associatedwith the RFID tag, the temperature of the liquid within the container, aliquid level of the liquid within the container, a timestamp associatedwith the response signal, a timestamp associated with the measurement ofliquid level, a timestamp associated with the temperature measurement,and/or a timestamp associated with the status/expiry of the liquidwithin the container. In some embodiments, such timestamp(s) and/ormeasurement value(s) (e.g., liquid level and temperature) may be storedin a memory associated with the RFID reader (e.g., a hard drive or incloud storage) upon the RFID reader receiving the response from the RFIDtag. Such measurements and times may, thereafter, be amalgamated intoplots of liquid level vs. time and/or liquid temperature vs. time.Additionally or alternatively, in some embodiments, the timestamp(s)and/or the measurement value(s) may be stored onboard a memory of theRFID tag (e.g., a memory associated the integrated circuit of the RFIDtag).

While many embodiments described herein include monitoring temperatureand/or liquid level of a container holding liquid contents, it isunderstood that other embodiments are contemplated herein. For example,in some embodiments, a container may hold a gas (e.g., a compressed gas)or a hybrid of a gas and a liquid (e.g., a propane fuel or a butanefuel). In such embodiments, the RFID tags described herein could also beused to monitor temperature within the container and/or a levelassociated with the contents in the container (e.g., a gas level or alevel of the hybrid gas/liquid). For example, an RFID tag as describedherein may be affixed to a tank filled with propane (e.g., a plastictank) and used to monitor the temperature of the propane mixture, aswell as a propane level. This may allow, for instance, a determinationof the amount of propane remaining in the tank without the need to weighthe tank or use some other device for determining propane level. A gaslevel or a hybrid gas/liquid level in a container may be determinedbased on a change in reactance associated with the antenna as theimpedance associated with the gas or the hybrid may change with density(e.g., as a compressed gas is depleted, the impedance associated withthat gas may change, thereby affecting the reactance associated with theantenna).

In addition to measuring and communicating a temperature and liquidlevel, embodiments herein may be used to monitor and/or communicationcertain statuses associated with the container. Such monitoring and/orcommunication may be performed in response to one or more triggers. Forexample, the integrated circuit may include a timer functionality. Upona certain amount of time expiring since the liquid (e.g., a vaccine) hasbeen diluted or since the container has been opened (e.g., the liquidhas been exposed to air, such as when a protective seal of the containeris breached or broken) a trigger may occur in the integrated circuit(e.g., a trigger may be set based on the integrated circuit executinginstructions stored within a memory). The trigger may cause the RFID tagto store a triggered status within a memory and/or to communicate thetriggered status to an RFID reader. As another example, a trigger mayoccur if the temperature of the container/associated liquid fallsoutside of a predetermined temperature range (e.g., rises above athreshold temperature stored within a memory and/or falls below athreshold temperature stored with a memory). This trigger may, forexample, cause the RFID tag to store a triggered status within a memorythat indicates that the contents of the container are spoiled/unusable(e.g., in the case of food products or drugs). Other examples oftriggers and related responses are also possible and are contemplatedherein.

II. Example Systems

The following description and accompanying drawings will elucidatefeatures of various example embodiments. The embodiments provided are byway of example, and are not intended to be limiting. As such, thedimensions of the drawings are not necessarily to scale.

Referring now to the figures, FIG. 1A is an illustration of a system100, according to example embodiments. The system 100 may include anRFID tag 110 and a container 120. FIG. 1B illustrates the same system100, but with the RFID tag 110 and portions of the container 120 beingtranslucent so that a liquid within the container 120 (e.g., a drug or avaccine within the container 120) is visible. It will be understood thatin some examples the container 120 need not be optically translucent ortransparent.

The RFID tag 110 may be used to identify the container 120. For example,an RFID reader may communicate with the RFID tag 110 to determine one ormore features of the container 120 or of the contents of the container120. For example, the RFID reader may communicate with the RFID tag 110to determine: what type of substance is within the container 120 (e.g.,a drug, a vaccine, a beverage, a fuel, etc.), an identification (ID)number of the container 120, a date of manufacture of the substancewithin the container 120, a date of expiration of the substance withinthe container 120, a date of expiration of the substance once thecontainer is opened, a proper dosage amount for the contents of thecontainer 120 (e.g., when the contents include a drug), a place oforigin of the container 120 and/or contents of the container 120, anintended place of delivery for the container 120, etc. In addition, asdescribed herein, the RFID tag 110 may additionally or alternativelyprovide information about a temperature and/or a liquid level for thecontents of the container 120 (e.g., in response to an RFID signal froman RFID reader).

In order to communicate with other devices (e.g., an RFID reader), theRFID tag 110 may include an antenna (e.g., a monopole or quarter-waveantenna, such as an antenna with an inverted L-type design, an invertedf-type design, or a half-wave antenna). The antenna may include groundplane 112 and a radiating plane 114.

Further, in order to process information and/or formulate messages totransmit to other devices, the RFID tag 110 may include an integratedcircuit. The integrated circuit may include an on-board memory, aprocessing device, an impedance sensor (e.g., to measure a reactanceassociated with the antenna), and/or one or more auxiliary sensors(e.g., temperature sensors, humidity sensors, pressure sensors, etc.).The RFID tag 110 will be further shown and described below withreference to FIG. 2A.

The container 120 may be penetrable by electromagnetic waves within theradio-frequency (RF) spectrum. As such, the reactance associated withthe antenna (e.g., a reactance of the antenna/liquid combination) may bemeasured. In some embodiments, an integrated circuit of the RFID tag 110may determine the liquid level of a liquid inside of the container 120by measuring the frequency response (e.g., within the RF spectrum, suchas the FCC spectrum from 902 MHz-928 MHz, the ETSI spectrum, or theWi-Fi spectrum) associated with the antenna (e.g., the antenna/liquidcombination). For example, when the container 120 is filled to a maximumlevel (e.g. full or the highest level it will ever reach, such as 10.0mL), the frequency response associated with the antenna may have a peakintensity corresponding to a first frequency, whereas when the container120 is filled to a minimum level (e.g., empty or the lowest level itwill ever reach, such as 0.5 mL), the frequency response associated withthe antenna may have a peak intensity corresponding to a secondfrequency. This is illustrated in FIG. 1C, where the frequency responseassociated with the antenna when the container 120 is at a first filllevel is illustrated by a solid line and the frequency responseassociated with the antenna when the container 120 is at a second filllevel is illustrated by a dashed line. As illustrated, the differencebetween the first frequency and the second frequency may be between 20MHz and 30 MHz, in some embodiments.

In some embodiments, this change in frequency response may berepresented as a percentage relative to the frequency response at agiven fill level. For example, if the center frequency at the minimumfill level (e.g., empty container) is 940 MHz and the center frequencyat the maximum fill level (e.g., full container) is 860 MHz, thefrequency response at maximum fill may be indicated as having a value of−8.51% (i.e., (860 MHz-940 MHz)/940 MHz). A range of these frequencyresponse values can be measured at different fill levels and then stored(e.g., in a plot and/or lookup table) for later use. FIG. 1D illustratesan example frequency response plot for the RFID tag 110. As indicated inthe plot, the change in frequency is represented as a percentagerelative to the frequency at the 0% fill level. For example, asillustrated, the change in frequency is: 0% at 0% fill level, about−0.1% at 25% fill level, about −0.6% at 50% fill level, about −1.5% at75% fill level, about −3% at 100% fill level, about −5.9% at 110% filllevel, and about −8.9% at 125% fill level. The points on the plot mayrepresent measured values of frequency response, while the linesconnecting the dots may represent interpolations. It is understood thatFIG. 1D is provided solely as an example and that other frequencyresponse values are also possible. For example, the amount of change inthe frequency based on fill level can be modified based on a size of thecontainer, a shape of the container, the type of liquid used, and/or orthe geometry of the antenna used (e.g., increasing the width of one ormore slots of a slot antenna may increase the overall change infrequency between 0% fill level and 125% fill level). A frequencyresponse curve/lookup table similar to that illustrated in FIG. 1D maybe stored (e.g., in a memory of the RFID tag 110 or an associated RFIDreader) and used to determine a fill level based on a measured resonantfrequency relative to the known resonant frequency at 0% fill level.

The antennas described herein (e.g., as illustrated and described withreference to FIG. 2 ) may include slot antennas. Slot antennas may havea less substantial frequency response than a dipole antenna (e.g., aninlay-type dipole antenna), for example. To illustrate this difference,the curve in the plot of FIG. 1D is replicated as a solid line in theplot of FIG. 1E and compared with the response of a theoretical dipoleantenna (illustrated by the dashed line in the plot of FIG. 1E). Asillustrated, while the change in frequency response may range from 0% toabout −3% from 0% to 100% fill level for the slot antenna describedherein, an alternative dipole antenna may have a change in frequencyresponse that ranges from 0% to about −30% from 0% to 100% fill level.In some cases, the variation may be even more than 0% to about −30%depending on the characteristics of the liquid within the container.Such a large range of operating frequencies for the alternative dipoleantenna may make the signals transmitted by the dipole antenna hard todetect (e.g., below the RFID frequency bands used by an associated RFIDreader) across the full range of fill levels. Hence, the slot antennamay have improved functionality across the full range of fill levelscompared to the dipole antenna.

This change in the frequency at peak intensity may be because the liquidwithin the container 120 has a different dielectric constant than airand/or is electrically conductive to some degree. Further, dielectricconstant can affect a substance's impedance (e.g., by affectingcapacitance) and/or how that impedance varies with excitation frequency.Hence, when the container 120 contains different proportions of liquidvs. air, a reactance associated with the contents of the container 120change. This change in reactance may be measured by the integratedcircuit using a variable set of capacitors within the RFID tag 110. Forexample, the integrated circuit may select a subset of capacitors tooptimize an RF response of the antenna of the RFID tag 110 (e.g., bymodifying the radiated frequency of emitted RF waves until the intensityof the emitted RF waves corresponds to a resonance of the antenna basedon the reactance associated with the antenna). Based on the selectedsubset of capacitors, a sensor code value can be determined. This sensorcode value may correspond to a predetermined sensor code value that isstored within a memory (e.g., within a lookup table) associated with theintegrated circuit. An example sensor code lookup table is illustratedin FIG. 1F. The sensor code lookup table illustrated may correspond to asensor code lookup table for the AXZON MAGNUS-S3 M3D integrated circuit,for example. As illustrated, the range of sensor codes (i.e., sensorcode values or code values) may range from about 0 to about 470. Otherranges are also possible and contemplated herein (e.g., based oncontainer size, container shape, or properties of the associated liquidwithin the container). The sensor codes may be a function of frequency(e.g., the sensor codes in FIG. 1F may vary with the transmissionfrequency of the antenna). As such, the sensor code may be measuredwhile transmitting a predetermined frequency value with the antenna suchthat the measurement can be properly correlated with the sensor codelookup table. Further, the sensor code lookup table may include sensorcodes corresponding to fill levels (e.g., measured in percent) from 0%(e.g., empty) to 125% (e.g., overfilled beyond recommended capacity) ormore. As illustrated, the sensor codes may be inversely related to thefill level. As examples from the sensor code lookup table illustrated inFIG. 1F, a fill level of 0% may correspond to a sensor code of about470, a fill level of 25% may correspond to a sensor code of about 442, afill level of 50% may correspond to a sensor code of about 320, a filllevel of 75% may correspond to a sensor code of about 141, a fill levelof 100% may correspond to a sensor code of about 55, a fill level of110% may correspond to a sensor code of about 20, and a fill level of125% may correspond to a sensor code of about 5. The sensor code lookuptable may include interpolated values. For example, there may bemeasured sensor codes relating to prescribed fill levels of 0%, 25%,50%, 75%, 100%, 110%, and 125% (represented by the dots on the plot ofFIG. 1F), and intervening sensor codes between those prescribed filllevels may be determined based on interpolation (represented by thesolid lines connecting the dots on the plot of FIG. 1F).

Further, the predetermined sensor code value stored within the memorymay correspond to a given reactance associated with the antenna (or,similarly, a given impedance associated with the antenna). Theintegrated circuit may transmit the given reactance to an RFID reader inresponse to an RFID signal to indicate a liquid level within thecontainer 120. Additionally or alternatively, the integrated circuit,itself, may determine a liquid level within the container 120 based onthe determined reactance and then may transmit the determined liquidlevel to the RFID reader.

Based on the above, when the peak intensity in the measured frequencyresponse is at the first frequency, the integrated circuit may determinethat the liquid level is at its maximum level (e.g., full oroverfilled), whereas when the peak intensity in the measured frequencyresponse is at the second frequency, the integrated circuit maydetermine that the liquid level is at its minimum level (e.g., empty).Additionally, the integrated circuit may determine liquid levels betweenthe maximum level and the minimum level by determining the frequencycorresponding to a peak in the frequency response associated with theRFID tag 110 and then interpolating between the first frequency and thesecond frequency. Such interpolated values may be determined (e.g., andlater communicated to the RFID reader) at various increments (e.g., 0.01mL, 0.05 mL, 0.1 mL, 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, 2.5 mL, 3.0 mL, 3.5mL, 4.0 mL, 4.5 mL, 5.0 mL, 10.0 mL, 50 mL, 100 mL, 500 mL, 1.0 L,etc.).

It is understood that such liquid levels may also correspond to dilutionlevels of the liquid within the container 120. For example, if theamount of solute in the container 120 is known, and a volume of theliquid is determined using the techniques described herein, theintegrated circuit of the RFID tag 110 (or another computing device,such as a computing device of an associated RFID reader) may determine adilution level. Further, it is understood that other differences betweenthe first frequency and the second frequency (besides between 20 MHz and30 MHz) are also possible (e.g., between 0 MHz and 5 MHz, between 5 MHzand 10 MHz, between 10 MHz and 15 MHz, between 15 MHz and 20 MHz,between 30 MHz and 35 MHz, or between 35 MHz and 40 MHz).

As described above, the peak intensity of the frequency response mayshift with changing volume of the liquid in the container 120. Inaddition, the intensity corresponding to any specific frequency withinthe spectrum will also change with changing liquid level. Hence,additionally or alternatively, the integrated circuit of the RFID tag110 may determine the liquid level of a liquid inside of the container120 by measuring a response associated with the antenna at apredetermined frequency. For example, the antenna may be designed with aspecific resonant frequency (e.g., a resonant frequency in the RFspectrum). The change in the magnitude of the response at that resonantfrequency may be measured by the integrated circuit to determine how theliquid level within the container 120 has changed.

Additionally, the container 120 may be specifically designed (e.g., inshape, size, and material) to house contents (e.g., gases, liquids(including mixtures or solutions), or solids) within the container 120.In some embodiments, the container 120, in various embodiments, may be aglass container. For example, the container 120 may be a glass beveragecontainer, such as a glass soda bottle, a glass beer bottle, a glasswine bottle, a glass liquor bottle, a pint glass, a wine glass, achampagne flute, a cocktail glass, etc. In other embodiments, thecontainer 120 may be configured to store biological samples, drugs, orvaccines (e.g., the container 120 may be a test tube, a slide, a vial, aflask, a beaker, a graduated cylinder, a petri dish, an intravenousfluid solution bag, a waste container, etc.). Additionally oralternatively, the container 120 may be a plastic container. Forexample, the container 120 may be a portable fuel tank or a plasticbeverage container, such as a 20 oz. soda bottle, a 2 L bottle, aplastic liquor bottle, etc. It is understood that other form factors,sizes, and shapes for containers are possible, and are contemplatedherein.

In some embodiments, the container 120 may also include one or morelabels (e.g., human-readable labels). Such labels may be placed on thecontainer 120 behind the RFID tag 110, on the container 120 adjacent tothe RFID tag 110, or on another location on the container 120 (e.g., ona cap of the container 120 or on a base of the container 120). Further,labels on the container 120 may be paper labels, polymer labels, ormetallic labels. In some embodiments, such labels may not interfere withthe RFID tag 110. In addition, the RFID tag 110 may be designed toaccommodate such labels so as to minimize or eliminate interferencebetween the label(s) and the RFID tag 110. Additionally oralternatively, one or more labels (e.g., human-readable labels) may beprinted on or otherwise disposed on the RFID tag 110.

FIG. 2A is an illustration of the RFID tag 110 illustrated in FIGS. 1Aand 1B, according to example embodiments. As illustrated, the RFID tag110 includes a ground plane 112 and a radiating plane 114. The RFID tag110 may also include an integrated circuit 116, as described above. Theground plane 112 and the radiating plane 114 may form a slot antenna, asillustrated in FIG. 2A. The length (e.g., x-dimension based on the axesillustrated in FIG. 2A) of the slot in which the radiating plane 114 isformed may be approximately equal to λ/4, λ/2, or integer multiples ofλ/4 or λ/2, where λ represents a wavelength (e.g., a center wavelengthor a most frequently used wavelength) of the signals radiated by theantenna of the RFID tag 110.

In some embodiments, the integrated circuit 116 may include an on-boardmemory and a processor. The processor may include one or moreprocessors, such as one or more general-purpose microprocessors and/orone or more special purpose microprocessors. The one or more processorsmay include, for instance, an application-specific integrated circuit(ASIC) or a field-programmable gate array (FPGA). Other types ofprocessors, computers, or devices configured to carry out softwareinstructions are contemplated herein.

The on-board memory may include a computer-readable medium, such as anon-transitory, computer-readable medium, which may include withoutlimitation, read-only memory (ROM), programmable read-only memory(PROM), erasable programmable read-only memory (EPROM), electricallyerasable programmable read-only memory (EEPROM), non-volatilerandom-access memory (e.g., flash memory), etc. The on-board memory ofthe integrated circuit 116 may include instructions that, when executedby the processor, may allow the processor to perform functionsincluding, but not limited to: measuring a frequency response associatedwhen the antenna and/or measuring the response of the antenna at a givenfrequency, determining a liquid level within the container 120 based onsuch measurements, communicating (e.g., receiving and transmittingsignals using the antenna) with an RFID reader, generating codes fortransmitting temperatures and/or liquid levels to the RFID reader,decoding instruction codes received from the RFID reader, determiningtimestamps associated events (e.g., transmissions received from the RFIDreader, transmissions to the RFID reader, liquid level measurements,temperature measurements, etc.), and storing data within the on-boardmemory. Notably, the integrated circuit 116 may execute instructionssuch that the RFID tag 110 communicates liquid levels within thecontainer 120 (e.g., with associated timestamps) and/or temperatures ofthe container 120 (e.g., with associated timestamps) to an RFID reader(e.g., in response to the RFID tag 110 receiving an RFID signal from theRFID reader). In some embodiments, such communications back to the RFIDreader may be based on a signal strength associated with the RFID signalreceived from the RFID reader.

The integrated circuit 116 may be connected to the antenna terminals(e.g., terminals of the ground plane 112 and the radiating plane 114)using inductive or capacitive coupling methods, in various embodiments.In addition, while not directly pictured, the integrated circuit 116 mayinclude on-board sensors (e.g., a temperature sensor, a humidity sensor,and/or a pressure sensor). These sensors can be used to monitor thecontainer 120, contents of the container 120, and/or a surroundingenvironment. Further, the readings of such sensors may be communicatedto an RFID reader and/or stored within the on-board memory of theintegrated circuit 116. For example, RFID tag 110 may be a passive RFIDtag that is energized by the RFID signal from the RFID reader. In suchembodiments, the readings of the sensors may be transiently stored inon-board memory (e.g., reserve memory, such as dynamic random-accessmemory (RAM)) while the RFID tag 110 is energized by the RFID signaluntil the readings can be communicated back to the RFID reader. Then,upon the RFID tag 110 become de-energized, the on-board memory may becleared. Hence, while in some embodiments the sensor readings and/orassociated timestamps may be stored long-term in an on-board memory ofthe RFID tag 110, in other embodiments, the on-board memory of the RFIDtag 110 may not retain the sensor readings after the RFID tag 110 hasbeen de-energized.

As illustrated in FIG. 2A, the ground plane 112 may be larger in surfacearea than the radiating plane 114. Further, the radiating plane 114 mayhave an aspect ratio (in width:height) of between 15:1 and 20:1 (e.g.,where 20:1 may be equal to a quarter of the radiating wavelength or halfof the radiating wavelength, which may be the minimum requirement toobtain antenna resonance), whereas the ground plane 112 may have anaspect ratio (in width:height) of between 2:1 and 5:1. In someembodiments, the antenna may be between 35 and 40 mm wide and between 10mm and 15 mm tall. However, other sizes and shapes for the ground plane112 and the radiating plane 114 are also possible and are contemplatedherein. For example, the ground plane 112 and the radiating plane 114need not be rectangular. For example, the ground plane 112 and/or theradiating plane 114 could have other shapes in other embodiments (e.g.,circular shapes, spiral shapes, interdigitated shapes, triangularshapes, square shapes, pentagonal shapes, hexagonal shapes, heptagonalshapes, octagonal shapes, nonagonal shapes, decagonal shapes, etc.).Further, aspects of the antenna (e.g., slots between the ground plane112 and the radiating plane 114 and/or dimensions, shapes, or materialsof the ground plane 112 and/or the radiating plane 114) may bedetermined based on the size of the container 120, a thickness of thecontainer 120, a shape of the container 120, a material of the container120, properties of the liquid within the container 120 (e.g., adielectric constant of the liquid contained within the container 120),and/or a chemical composition of the liquid within the container 120.Hence, different containers 120 with different liquid contents may havedifferently sized and shaped antennae. For example, if the container 120is a 1.0 L bottle of whiskey, the antenna may run from the top of thecontainer 120 to the bottom of the container 120 (e.g., the antenna maybe about 150 mm in length). Further, an antenna designed for use withsuch a container 120 may be roughly triangular in shape (e.g., about 20mm wide at the top of the antenna and about 1 mm wide at a bottom of theantenna).

The readings from the temperature sensor and/or the liquid leveldetermined based on the reactance associated with the antenna may becommunicated to an RFID reader in response to an RFID signal using acode value, in some embodiments. For example, in various embodiments,the liquid level may correspond to a code value between 0 and 255,between 0 and 100, or between 5 and 470 depending on fill level withinthe container 120. Additionally or alternatively, a temperature offsetcode based on calibration data may be used to convert a reading from atemperature sensor into a proper temperature value. Such liquid-leveland/or temperature code values may be stored within a lookup table of anon-board memory of the integrated circuit 116 and looked up by theintegrated circuit 116 based on a determined reactance associated withthe antenna when determining liquid level and/or when communicating withan RFID reader. Further, in some embodiments, code values associatedwith sensor(s) (e.g., the temperature sensor) on the RFID tag 110 may bethe only information stored within the on-board memory. Such embodimentsmay allow the on-board memory to be relatively small in terms of storagespace, for example.

In some embodiments, the on-board memory may store identificationinformation about the RFID tag 110 (e.g., a tag identifier such as anidentification code, an identification number, or an electronic productcode (EPC)). In some embodiments, in order to prevent malicioustampering with the sensor code values, tag-identification information,and/or other information stored within the on-board memory of the RFIDtag 110, the on-board memory may be locked. In other words, the on-boardmemory may not be written to (either by an RFID reader or a third-partydevice) once the RFID tag 110 has been designated for use. In somecases, this may prevent an end-user from reprogramming static sensorcode values or communication protocols of the on-board memory,counterfeiting the RFID tag 110, and/or repurposing the RFID tag 110.

As described above, the RFID tag 110 may include a slot antenna (e.g.,that includes the ground plane 112 and the radiating plane 114). Theslot antenna may represent an alternative to dipole antennaarrangements. As also described above, the sensor code values measuredby the associated integrated circuit 116, the reactance of the antennameasured by the associated integrated circuit 116, and/or the resonantfrequency/wavelength of the antenna may change as a result of a changein the liquid level in the container. These change(s) may be accompaniedby and/or a result of a change in the surface current along regions ofthe antenna of the RFID tag 110 (e.g., along portions of the groundplane 112 and/or the radiating plane 114) as a result of the liquidlevel of the container changing. An example change in surface current isillustrated in FIGS. 2B and 2C.

FIG. 2B is a plot 210 of the surface current (e.g., in amps/meter) ofthe RFID tag 110 (illustrated three-dimensionally as a flat plane curvedabout the vertical axis) when the container around which the RFID tag110 is wrapped has a 0% fill level (e.g., when the container is empty).FIG. 2B includes a key 212 indicating the surface current correspondingto the coloration.

Similarly, FIG. 2C is a plot 220 of the surface current (e.g., inamps/meter) of the RFID tag 110 (illustrated three-dimensionally as aflat plane curved about the vertical axis) when the container aroundwhich the RFID tag 110 is wrapped has a 100% fill level (e.g., when thecontainer is full). FIG. 2C includes a key 222 indicating the surfacecurrent corresponding to the coloration. The coloration andcorresponding surface currents in the key 222 of FIG. 2C are the same asin the key 212 of FIG. 2B. Hence, a direct comparison can be madebetween FIGS. 2B and 2C. By comparing the surface currents illustratedin FIGS. 2B and 2C, it is clear that that surface current issignificantly higher, generally, when the container has a 100% filllevel (e.g., as illustrated in FIG. 2C).

In addition to the surface current being modified when the fill level ofthe corresponding container is changed, the directivity of the antennaof the RFID tag 110 (e.g., as measured based on radiative signalintensity) may also change when the fill level changes. FIG. 2D is aplot 230 of the directivity (e.g., in dB) of the antenna of the RFID tag110 when the associated container has a 0% fill level. FIG. 2D includesa key 232 indicating the relative directivity corresponding to thecoloration. Likewise, FIG. 2E is a plot 240 of the directivity (e.g., indB) of the antenna of the RFID tag 110 when the associated container hasa 100% fill level. FIG. 2E includes a key 242 indicating the relativedirectivity corresponding to the coloration. As illustrated by therelative shapes and coloration, the antenna of the RFID tag 110 has moredirectionality when the container has a 0% fill level. This featurecould be measured by an RFID reader based on radiative intensity ofsignals radiated by the antenna, for example, and could be used (e.g.,by the RFID reader) to determine liquid level within the container.

FIG. 3 is an illustration of a system 300, according to exampleembodiments. The system 300 may include an RFID reader 302 and acontainer equipped with an RFID tag (e.g., the container 120 equippedwith the RFID tag 110 shown and described with reference to FIGS. 1A,1B, and 2 ). The RFID reader 302 may be configured to read informationfrom one or more RFID tags in order to identify the objects to which theRFID tags are attached. As described herein, the RFID reader 302 may beable to communicate with the RFID tag 110 in order to determine thecontents of the container 120, a volume of a liquid within the container120, and/or a temperature of a liquid within the container 120.

The RFID reader 302 may communicate with the RFID tag 110 bytransmitting an RFID signal to the RFID tag 110. As such, the RFIDreader 302 may include a power source (e.g., a battery, a capacitor, ora connection to an electrical outlet), a transmitter, and a receiver.The transmitter may be configured to emit the RFID signal at apredetermined frequency to communicate with the RFID tag 110. Further,the RFID signal may include one or more identifying characteristics(e.g., modulation frequency, communication code, etc.) to indicate tothe RFID tag 110 that the RFID reader 302 is authorized to receiveinformation from the RFID tag 110 about the container 120 (e.g., toreceive information about the liquid level of the container 120 or thecontents of the container 120). The receiver of the RFID tag 110 mayreceive information communicated by the RFID tag 110 back to the RFIDreader 302.

In some embodiments, the RFID reader 302 may have an associated memory(e.g., a computer-readable medium, such as a ROM, a hard drive, a RAM,or cloud storage). Such a memory may be on-board the RFID reader 302and/or communicatively coupled to the RFID reader 302. The communicativecoupling may be via a wired connection (e.g., a connection over auniversal serial bus (USB) cable) or a wireless connection (e.g., aconnection of WIFI® or BLUETOOTH®). The memory may be configured tostore data received from the RFID tag 110 for later access/review. Forexample, the memory may store one or more liquid levels and/or liquidtemperatures associated with the container 120 and the RFID 110 based oninformation received from the RFID tag 110. Further, in someembodiments, the RFID reader 302 may receive timestamps from the RFIDtag 110 associated with one or more of the liquid level measurementsand/or one or more of the temperature measurements. Such timestamps maylikewise be stored in a memory of the RFID reader 302. Additionally oralternatively, liquid level measurements, temperature measures,expiration status, etc. may be communicated by the RFID reader (e.g.,over WIFI, BLUETOOTH, ETHERNET connection, cellular network, etc.) to bestored in a cloud storage location or in a remote data center for lateraccess.

It is understood that the information stored in a memory of the RFIDreader 302 may be additionally and/or alternatively stored on a memoryassociated with the RFID tag 110 (e.g., an on-board memory of the RFIDtag 110) and/or on an auxiliary memory that is associated with neitherthe RFID reader 302 nor the RFID tag 110. For example, an auxiliarymemory may receive and store a series of timestamps and associatedliquid levels and temperatures from the RFID reader 302 in response tothe RFID reader 302 receiving data from the RFID tag 110. In someembodiments, the auxiliary memory may be associated with apharmaceutical corporation, a drug manufacturer, a drug distributed, acommon carrier (e.g., a delivery service), and/or a governmental agency(e.g., the Food and Drug Administration (FDA), the National Institute ofHealth (NIH), or the Centers for Disease Control and Prevention (CDC)).In some embodiments, such an auxiliary memory may not be read by eitherthe RFID reader 302 or the RFID tag 110.

III. Example Processes

FIG. 4 is a flowchart diagram of a method 400, according to exampleembodiments. The method 400 may be performed by the RFID tag 110 ofFIGS. 1A-3 , for example.

At block 402, the method 400 may include receiving, at a radio-frequencyidentification (RFID) tag, an RFID signal transmitted by an RFID reader.The RFID tag includes an antenna. The antenna includes a radiatingplane. The antenna also includes a ground plane. The RFID tag isattached to a container. A reactance associated with the antenna ismodifiable based on a volume of a liquid within the container andproximate to the ground plane. The RFID tag also includes an integratedcircuit that includes a memory, and a temperature sensor configured toprovide information indicative of a temperature of the liquid within thecontainer.

At block 404, the method 400 may include modulating, by the integratedcircuit in response to the RFID signal, the antenna based on thereactance associated with the antenna, and a temperature reading of thetemperature sensor to provide information indicative of the volume ofthe liquid within the container and the temperature of the liquid withinthe container.

IV. CONCLUSION

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims.

The above detailed description describes various features and functionsof the disclosed systems, devices, and methods with reference to theaccompanying figures. In the figures, similar symbols typically identifysimilar components, unless context dictates otherwise. The exampleembodiments described herein and in the figures are not meant to belimiting. Other embodiments can be utilized, and other changes can bemade, without departing from the scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein.

With respect to any or all of the message flow diagrams, scenarios, andflow charts in the figures and as discussed herein, each step, block,operation, and/or communication can represent a processing ofinformation and/or a transmission of information in accordance withexample embodiments. Alternative embodiments are included within thescope of these example embodiments. In these alternative embodiments,for example, operations described as steps, blocks, transmissions,communications, requests, responses, and/or messages can be executed outof order from that shown or discussed, including substantiallyconcurrently or in reverse order, depending on the functionalityinvolved. Further, more or fewer blocks and/or operations can be usedwith any of the message flow diagrams, scenarios, and flow chartsdiscussed herein, and these message flow diagrams, scenarios, and flowcharts can be combined with one another, in part or in whole.

A step, block, or operation that represents a processing of informationcan correspond to circuitry that can be configured to perform thespecific logical functions of a herein-described method or technique.Alternatively or additionally, a step or block that represents aprocessing of information can correspond to a module, a segment, or aportion of program code (including related data). The program code caninclude one or more instructions executable by a processor forimplementing specific logical operations or actions in the method ortechnique. The program code and/or related data can be stored on anytype of computer-readable medium such as a storage device including RAM,a disk drive, a solid state drive, or another storage medium.

Moreover, a step, block, or operation that represents one or moreinformation transmissions can correspond to information transmissionsbetween software and/or hardware modules in the same physical device.However, other information transmissions can be between software modulesand/or hardware modules in different physical devices.

The particular arrangements shown in the figures should not be viewed aslimiting. It should be understood that other embodiments can includemore or less of each element shown in a given figure. Further, some ofthe illustrated elements can be combined or omitted. Yet further, anexample embodiment can include elements that are not illustrated in thefigures.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims.

Embodiments of the present disclosure may thus relate to one of theenumerated example embodiments (EEEs) listed below.

EEE 1 is a radio-frequency identification (RFID) tag comprising:

-   -   an antenna configured to communicate with an RFID reader,        wherein the antenna comprises:        -   a radiating plane; and        -   a ground plane,        -   wherein the RFID tag is attachable to a container, and        -   wherein a reactance associated with the antenna is            modifiable based on a    -   volume of a liquid within the container and proximate to the        ground plane; and    -   an integrated circuit comprising a memory and a temperature        sensor configured to provide information indicative of a        temperature of the liquid within the container, wherein the        integrated circuit is configured to:    -   in response to an RFID signal from the RFID reader, modulate the        antenna based on the reactance associated with the antenna and a        temperature reading of the temperature sensor to provide        information indicative of the volume of the liquid within the        container and the temperature of the liquid within the        container.

EEE 2 is the RFID tag of EEE 1,

-   -   wherein the container is a glass container, and    -   wherein the RFID tag is attachable to the container such that        the ground plane is touching the glass container.

EEE 3 is the RFID tag of EEE 1,

-   -   wherein the container is a plastic container, and    -   wherein the RFID tag is attachable to the container such that        the ground plane is touching the plastic container.

EEE 4 is the RFID tag of any of EEEs 1-3, wherein the container ispenetrable by electromagnetic waves within the radio-frequency (RF)spectrum.

EEE 5 is the RFID tag of any of EEEs 1-4, wherein the integrated circuitis configured to determine the reactance associated with the antenna bymeasuring a response associated with the antenna at a predeterminedfrequency.

EEE 6 is the RFID tag of any of EEEs 1-5, wherein the integrated circuitis configured to determine the reactance associated with the antenna bymeasuring a frequency response associated with the antenna.

EEE 7 is the RFID tag of EEE 6,

-   -   wherein a peak intensity of the frequency response corresponds        to a first frequency when the volume of the liquid is at a        maximum level of the liquid within the container,    -   wherein the peak intensity of the frequency response corresponds        to a second frequency when the volume of the liquid is at a        minimum level of the liquid within the container, and    -   wherein a difference between the first frequency and the second        frequency is between 3% and 10%.

EEE 8 is the RFID tag of EEE 7,

-   -   wherein the antenna further comprises a slot between the        radiating plane and the ground plane, and    -   wherein the slot is configured to be positioned above the        maximum level of the liquid within the container or near the        maximum level of the liquid within the container.

EEE 9 is the RFID tag of any of EEEs 1-8,

-   -   wherein modulating the antenna in response to the RFID signal        comprises:        -   determining a code value from a lookup table based on the            reactance associated with the antenna; and        -   communicating the code value to the RFID reader, and    -   wherein the lookup table is stored within the memory.

EEE 10 is the RFID tag of any of EEEs 1-9, wherein a size of theradiating plane, a size of the ground plane, a shape of the radiatingplane, a shape of the ground plane, a material of the radiating plane,or a material of the ground plane is based on:

-   -   a chemical composition of the liquid;    -   properties of the liquid;    -   a size of the container;    -   a thickness of the container;    -   a material of the container; or    -   a shape of the container.

EEE 11 is the RFID tag of any of EEEs 1-10,

-   -   wherein the radiating plane has an aspect ratio, in        width:height, of between 15:1 and 20:1, and    -   wherein the ground plane has an aspect ratio, in width:height,        of between 2:1 and 5:1.

EEE 12 is the RFID tag of any of EEEs 1-11, wherein the containercomprises a paper label, a polymer label, or a metallic label.

EEE 13 is the RFID tag of any of EEEs 1-12, wherein the liquid comprisesa biological sample.

EEE 14 is the RFID tag of EEE 13, wherein the container is a test tube.

EEE 15 is the RFID tag of any of EEEs 1-12, wherein the liquid comprisesa beverage.

EEE 16 is the RFID tag of EEE 15, wherein the container is a glassbottle or a plastic bottle.

EEE 17 is the RFID tag of any of EEEs 1-12, wherein the liquid comprisesa vaccine.

EEE 18 is the RFID tag of EEE 17, wherein the container is a vial.

EEE 19 is the RFID tag of any of EEEs 1-12, wherein the liquid comprisesa fuel.

EEE 20 is the RFID tag of EEE 19, wherein the container is a fuel tank.

EEE 21 is the RFID tag of any of EEEs 1-12, wherein the container is avial, a test tube, a beverage can, a glass beverage bottle, a fuelcontainer, an intravenous fluid solution bag, a waste container, or awater reservoir.

EEE 22 is the RFID tag of any of EEEs 1-21, wherein the radiating planeis triangular in shape.

EEE 23 is the RFID tag of any of EEEs 1-22, wherein the ground plane istriangular in shape.

EEE 24 is the RFID tag of any of EEEs 1-23, wherein the integratedcircuit is further configured to, in response to the RFID signal fromthe RFID reader, modulate the antenna to provide information indicativeof:

-   -   a universal expiry date of the liquid within the container;    -   an expiry date once the container has been opened;    -   an amount of time elapsed since the container has been opened;        or    -   a time at which the temperature reading fell outside of a        predetermined temperature range.

EEE 25 is the RFID tag of any of EEEs 1-24, wherein the integratedcircuit is electrically coupled to one or more terminals of the antennavia inductive coupling or capacitive coupling.

EEE 26 is a system comprising:

-   -   a container configured to be filled with a liquid; and    -   a radio-frequency identification (RFID) tag attached to the        container, wherein the RFID tag comprises:        -   an antenna configured to communicate with an RFID reader,            wherein the antenna comprises:            -   a radiating plane; and            -   a ground plane, wherein a reactance associated with the                antenna is modifiable based on a volume of the liquid                within the container and        -   proximate to the ground plane; and        -   an integrated circuit comprising a memory and a temperature            sensor,    -   wherein the temperature sensor is configured to provide        information indicative of a temperature of the liquid within the        container, wherein the integrated circuit is configured to:        -   in response to an RFID signal from the RFID reader, modulate            the antenna based on the reactance associated with the            antenna and a temperature reading of the temperature sensor            to provide information indicative the volume of the liquid            within the container and the temperature of the liquid            within the container.

EEE 27 is the system of EEE 26, wherein the integrated circuit isfurther configured to modulate the antenna in response to the RFIDsignal from the RFID reader based on a signal strength of the RFIDsignal.

EEE 28 is a method comprising:

-   -   receiving, at a radio-frequency identification (RFID) tag, an        RFID signal transmitted by an RFID reader, wherein the RFID tag        comprises:        -   an antenna comprising:            -   a radiating plane; and            -   a ground plane,            -   wherein the RFID tag is attached to a container, and            -   wherein a reactance associated with the antenna is                modifiable based on a volume of a liquid within the                container and proximate to the ground plane; and        -   an integrated circuit comprising a memory and a temperature            sensor configured to provide information indicative of a            temperature of the liquid within the container; and        -   modulating, by the integrated circuit in response to the            RFID signal, the antenna based on the reactance associated            with the antenna and a temperature reading of the            temperature sensor to provide information indicative of the            volume of the liquid within the container and the            temperature of the liquid within the container.

EEE 29 is the method of EEE 28, wherein modulating the antenna furtherprovides information indicative of a time stamp.

EEE 30 is the method of EEEs 28 or 29, wherein the volume of the liquidwithin the container is determined to a nearest 0.5 mL increment.

EEE 31 is the method of any of EEEs 28-30, further comprising storingthe volume of the liquid and an associated time stamp in a memoryassociated with the RFID reader.

What is claimed is:
 1. A radio-frequency identification (RFID) tagcomprising: an antenna configured to communicate with an RFID reader,wherein the antenna comprises a ground plane, wherein the RFID tag isattachable to a container, and wherein a reactance associated with theantenna is modifiable based on a volume of a liquid within the containerand proximate to the ground plane; and an integrated circuit comprisinga memory, wherein the integrated circuit is configured to, in responseto an RFID signal from the RFID reader, modulate the antenna based onthe reactance associated with the antenna to provide informationindicative of the volume of the liquid within the container.
 2. The RFIDtag of claim 1, wherein the container is a glass container, and whereinthe RFID tag is attachable to the container such that the ground planeis touching the glass container.
 3. The RFID tag of claim 1, wherein thecontainer is a plastic container, and wherein the RFID tag is attachableto the container such that the ground plane is touching the plasticcontainer.
 4. The RFID tag of claim 1, wherein the container ispenetrable by electromagnetic waves within the radio-frequency (RF)spectrum.
 5. The RFID tag of claim 1, wherein the integrated circuit isconfigured to determine the reactance associated with the antenna bymeasuring a response associated with the antenna at a predeterminedfrequency.
 6. The RFID tag of claim 1, wherein the integrated circuit isconfigured to determine the reactance associated with the antenna bymeasuring a frequency response associated with the antenna.
 7. The RFIDtag of claim 6, wherein a peak intensity of the frequency responsecorresponds to a first frequency when the volume of the liquid is at amaximum level of the liquid within the container, wherein the peakintensity of the frequency response corresponds to a second frequencywhen the volume of the liquid is at a minimum level of the liquid withinthe container, and wherein a difference between the first frequency andthe second frequency is between 3% and 10%.
 8. The RFID tag of claim 7,wherein the antenna further comprises: a radiating plane; and a slotbetween the radiating plane and the ground plane, and wherein the slotis configured to be positioned above the maximum level of the liquidwithin the container or near the maximum level of the liquid within thecontainer.
 9. The RFID tag of claim 1, wherein modulating the antenna inresponse to the RFID signal comprises: determining a code value from alookup table based on the reactance associated with the antenna; andcommunicating the code value to the RFID reader, and wherein the lookuptable is stored within the memory.
 10. The RFID tag of claim 1, whereinthe antenna further comprises a radiating plane, and wherein a size ofthe radiating plane, a size of the ground plane, a shape of theradiating plane, a shape of the ground plane, a material of theradiating plane, or a material of the ground plane is based on: achemical composition of the liquid; properties of the liquid; a size ofthe container; a thickness of the container; a material of thecontainer; or a shape of the container.
 11. The RFID tag of claim 1,wherein the antenna further comprises a radiating plane, wherein theradiating plane has an aspect ratio, in width:height, of between 15:1and 20:1, and wherein the ground plane has an aspect ratio, inwidth:height, of between 2:1 and 5:1.
 12. The RFID tag of claim 1,wherein the antenna further comprises a radiating plane, wherein thecontainer comprises a paper label, a polymer label, or a metallic label,wherein the liquid comprises a biological sample, a beverage, a vaccine,or a fuel, wherein the container comprises a test tube, a glass bottle,a plastic bottle, a vial, a fuel tank, a beverage can, an intravenoussolution bag, a waste container, or a water reservoir, and wherein theradiating plane is triangular in shape or the ground plane is triangularin shape.
 13. The RFID tag of claim 1, wherein the integrated circuit isfurther configured to, in response to the RFID signal from the RFIDreader, modulate the antenna to provide information indicative of: auniversal expiry date of the liquid within the container; an expiry dateonce the container has been opened; or an amount of time elapsed sincethe container has been opened.
 14. The RFID tag of claim 1, wherein theintegrated circuit is electrically coupled to one or more terminals ofthe antenna via inductive coupling or capacitive coupling.
 15. A systemcomprising: a container configured to be filled with a liquid; and aradio-frequency identification (RFID) tag attached to the container,wherein the RFID tag comprises: an antenna configured to communicatewith an RFID reader, wherein the antenna comprises a ground plane, andwherein a reactance associated with the antenna is modifiable based on avolume of the liquid within the container and proximate to the groundplane; and an integrated circuit comprising a memory, wherein theintegrated circuit is configured to, in response to an RFID signal fromthe RFID reader, modulate the antenna based on the reactance associatedwith the antenna to provide information indicative the volume of theliquid within the container.
 16. The system of claim 15, wherein theintegrated circuit is further configured to modulate the antenna inresponse to the RFID signal from the RFID reader based on a signalstrength of the RFID signal.
 17. A method comprising: receiving, at aradio-frequency identification (RFID) tag, an RFID signal transmitted byan RFID reader, wherein the RFID tag comprises: an antenna comprising aground plane, wherein the RFID tag is attached to a container, andwherein a reactance associated with the antenna is modifiable based on avolume of a liquid within the container and proximate to the groundplane; and an integrated circuit comprising a memory; and modulating, bythe integrated circuit in response to the RFID signal, the antenna basedon the reactance associated with the antenna to provide informationindicative of the volume of the liquid within the container.
 18. Themethod of claim 17, wherein modulating the antenna further providesinformation indicative of a time stamp.
 19. The method of claim 17,wherein the volume of the liquid within the container is determined to anearest 0.5 mL increment.
 20. The method of claim 17, further comprisingstoring the volume of the liquid and an associated time stamp in amemory associated with the RFID reader.